Animals, particularly companion animals (e.g., dogs and cats), may weigh more than their ideal body weight. Having an excess of adipose tissue, these animals may be clinically diagnosed as, e.g., “fat”, “overweight”, or “obese” and, as such, are more likely to suffer from associated physical disorders such as arthritis, heart disease, respiratory disease, diabetes, bladder cancer, hypothyroidism, joint disease and/or pancreatitis.
Attempts to prevent or reduce the amount of excess adipose tissue on companion animals typically include dietary restriction and exercise. Indeed, many “low” or “reduced” calorie foods for overweight companion animals have been developed and are commercially available for the control of calorie intake, prevention of weight gain or for the promotion of weight loss. One strategy in weight loss involves high protein diets with high protein to calorie ratios in order to reduce the amount of body fat in humans. A similar approach has been used in companion animal products (e.g. PRESCRIPTION DIET® FELINE M/D®, Hill's Pet Nutrition, Topeka, Kans.). High protein diets have proven to be effective in weight loss in cats; however high protein foods have had mixed results when applied to canine weight management programs. Treatment strategies also include increasing the fiber and/or protein content while reducing the fat in the food. Depending on the fiber source, the fiber can induce satiety via gut distention or through feedback mechanisms (e.g., GLP-1). Fiber can be effective in reducing the digestibility of food resulting in a lower availability of high calorie nutrient components (i.e. fat and carbohydrates).
Despite the availability of such pet food formulations, however, the need remains for the development of additional formulations comprising innovative ingredients and nutrients for preventing or treating obesity in companion animals. For example, one problem with weight loss is that lean muscle mass is commonly lost as a component of total body weight loss even though it is not the target tissue. Thus, there is a need for compositions which can cause weight loss in animals without causing loss of lean muscle mass.
We have now surprisingly discovered that a weight loss composition formulated to include a specific balance of essential and limiting amino acids can cause weight loss that is characterized by a preservation or gain of lean muscle. Thus, as contemplated herein, the compositions of the present invention may be useful to prevent or treat obesity in an animal without the concomitant loss of lean muscle in the animal.
Essential amino acids are amino acids that cannot be synthesized de novo, or in sufficient quantities by an organism and thus must be supplied in the diet. Essential amino acids vary from species to species, depending upon the organism's metabolism. For example, it is generally understood that the essential amino acids for dogs and cats (and humans) are phenylalanine, leucine, methionine, lysine, isoleucine, valine, threonine, tryptophan, histidine and arginine. In addition, taurine, while technically not an amino acid but a derivative of cysteine, is an essential nutrient for cats. A balanced diet can provide all the essential amino acids, however, there are certain essential amino acids that are more critical, as a diet deficient in one of them will limit the usefulness of the others, even if the other essential amino acids are present in sufficient quantities. Generally, these limiting amino acids are methionine, cysteine, tryptophan, and lysine.